What is the workup for lymphangitis?

Workup for Lymphangitis

The workup for lymphangitis should focus on identifying the underlying infectious or non-infectious etiology through clinical assessment, blood cultures when systemic infection is suspected, and tissue sampling for atypical presentations, with empiric antibiotic therapy initiated promptly for bacterial causes while awaiting culture results.

Clinical Assessment

History and Physical Examination

• Document the timeline of symptom development, as bacterial lymphangitis typically develops within 24-72 hours of inoculation, while fungal or mycobacterial causes may have longer incubation periods (weeks to months) 1
• Identify the portal of entry: Look for evidence of trauma, insect bites, or pre-existing skin lesions (paronychia, wounds, ulcers) that could serve as the inoculation site 2, 1
• Assess for characteristic linear erythematous streaks extending from the site of infection toward regional lymph nodes, which is the hallmark finding 3, 2
• Evaluate for systemic symptoms including fever, chills, and malaise that suggest bacteremia or more serious infection requiring infectious disease consultation 4
• Examine regional lymph nodes for tenderness, enlargement, or fluctuance 1

Distinguish Clinical Patterns

• Acute superficial lymphangitis presents with rapid onset (24-72 hours) and is typically caused by pyogenic bacteria (Streptococcus, Staphylococcus) 5, 2
• Nodular (sporotrichoid) lymphangitis presents with subcutaneous nodules along lymphatic channels and suggests fungal (Sporothrix schenckii), mycobacterial (Mycobacterium marinum), or parasitic (Leishmania) etiologies 1

Laboratory Evaluation

Initial Blood Work

• Complete blood count with differential to assess for leukocytosis, left shift, or other abnormalities suggesting systemic infection 6
• Blood cultures should be obtained if the patient appears systemically ill, has fever, or shows signs of bacteremia before initiating antibiotics 6
• Basic metabolic panel to assess renal function and electrolytes, particularly if systemic antibiotics will be required 6

Microbiologic Studies

• Bacterial cultures from the portal of entry (wound, abscess, ulcer) should be obtained when possible, though the presence of lymphangitic streaking does not predict specific pathogens 7
• Tissue biopsy with special stains and cultures is essential for nodular lymphangitis or cases failing empiric therapy, including:
  • Routine bacterial cultures
  • Fungal cultures (Sporothrix)
  • Acid-fast bacilli stains and mycobacterial cultures (Mycobacterium marinum, Nocardia)
  • Histopathology with special stains 1

Epidemiologic and Exposure History

Key Questions to Guide Differential Diagnosis

• Occupational and recreational exposures: Gardening or rose handling (Sporothrix), aquarium exposure (M. marinum), soil contact (Nocardia), travel to endemic areas (Leishmania, tularemia) 1
• Animal exposures: Cat scratches or bites (Francisella tularensis), wild animal contact 1
• Immunocompromise status: HIV, diabetes, immunosuppressive medications, which increase risk for atypical organisms 4
• Recent arthropod bites: Mosquito or other insect bites can cause non-infectious lymphangitis that resolves without antibiotics 2

Imaging Studies

Imaging is generally not required for straightforward acute bacterial lymphangitis but may be indicated in specific circumstances:

• Ultrasound can identify underlying abscess formation requiring drainage 4
• CT or MRI may be needed if deep tissue involvement, osteomyelitis, or necrotizing infection is suspected 4

Management Approach Based on Clinical Presentation

Acute Bacterial Lymphangitis (Most Common)

• Initiate empiric antibiotics covering Streptococcus and Staphylococcus (including MRSA in high-prevalence areas) without waiting for culture results, as Staphylococcus aureus (MSSA 40%, MRSA 26%) and Streptococcus are the predominant pathogens 7
• Consult infectious disease if the patient has signs of systemic infection, immunocompromise, or fails to improve within 48-72 hours 4

Nodular Lymphangitis

• Obtain tissue biopsy before initiating therapy as empiric treatment differs significantly based on organism (itraconazole for Sporothrix, trimethoprim-sulfamethoxazole for Nocardia, clarithromycin for M. marinum) 1
• Consider empiric antifungal therapy (itraconazole) for sporotrichosis if clinical suspicion is high and biopsy will be delayed, as this is the most common cause of nodular lymphangitis 1

Non-Infectious Lymphangitis

• Avoid unnecessary antibiotics in cases clearly related to arthropod bite reactions or other non-infectious causes, which can resolve spontaneously within days 2

Critical Pitfalls to Avoid

• Do not assume all lymphangitis is bacterial: Non-infectious causes (arthropod bites) and atypical organisms (fungi, mycobacteria) require different management 2, 1
• Do not delay tissue diagnosis in nodular lymphangitis: Empiric antibiotics for bacterial infection will fail, and specific cultures/stains are required 1
• Do not overlook immunocompromise: Patients with HIV, diabetes, or on immunosuppressive therapy require broader workup and infectious disease consultation 4
• Do not miss systemic infection: Failure to recognize bacteremia or deeper infection can lead to serious complications including sepsis 4